April 4, 2007
Application of Preemergence Herbicides to Lawns
Crabgrass is a annual warm season grass and a common weed in many lawns. Crabgrass seeds begin to germinate when soil temperatures reach 55°F. Germination usually begins about mid-April in southern Iowa, early May in northern parts of the state, and continues to germinate over several weeks from spring into summer.
Yellowing of Spruce
We occasionally receive spruce samples in the Plant Disease Clinic that show yellowing of the needles, sometimes only older needles and sometimes both older and younger needles. Such symptoms are rarely a result of infectious disease.